I would just like to know the reason(s) behind this decision (Pros./Cons. of using Qt and NUX). Thank you very much and keep on the awesome work! Ubuntu rocks! :D
Nux wasn't exactly chosen - it was created from scratch and is developed alongside Unity. For some information on what it is and the benefits see this posting from Unity developer Jason Smith. Also there is a question that goes into much more detail on the inner workings of Nux.
Qt has recently been praised by Canonical's Matt Zimmerman on his blog for being stable on ARM platforms as well as x86; for being cross platform; and for having a mature touch input system.
I know this doesn't completely answer your question but it gives some insight into reasoning behind these decisions.